Water filtration has become common in homes, offices and other places to produce cleaner and better tasting water. Common filtration systems include water pitcher filtration, refrigeration filtration, faucet filtration, and the like. The filtration devices include a filter through which the water passes to remove particles, chemicals, microbes and the like. For proper operation, the filters should be changed periodically.
A number of techniques have been employed to indicate when to replace the filter on water pitcher type filtration devices. Because of the nature of water pitcher type filtration devices, the techniques for indicating when to replace the filter are more limited than the other types of filtration systems. Some techniques use a flow sensor or a float sensor that makes contact with the water, a switch coupled to a fill lid, or the like, to measure the amount of water being filtered. Such techniques are relatively complicated to manufacture, may themselves introduce impurities and/or microbes into the water as a result of the contact with the water. Other techniques use a timer and output a signal to the user to change the filter after a predetermined period of time. However, if the water pitcher is used more often than the predetermined time is based upon, the filter may need to be changed more often than the time indicates. Accordingly, there is a continuing need for improved techniques for monitoring the status of the filter and indicating when to change the filter.